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Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 26 Dec 2017 13:07
by hugejp
karldDanneberg wrote: 26 Dec 2017 13:02 was there any change to your fuel consumption?
She definitely did have more pep on pick-up & economy did improve

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 07:47
by Louis Nel
I would not blow it with compressed air, I dono much about them but I'm pretty sure it looks the same as the 4.5's MAF.
That thing has a very thin wire in there, rather get MAF cleaner and spray with that.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 08:51
by hugejp
Yip!
Compressed air is not the best idea.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 12:36
by karldDanneberg
Havent sprayed or cleaned the MAF yet, I purchased Electronic Cleaner by Herschell for MAF cleaning tomorrow.

In the mean while, I disconnected the -ve terminal for a couple hours. It seemed as though it improved, until I was cruising slowly uphill at 2000 rpm and I switched the headlights on...the sputtering returned. This is rather suspicious, before I conclude this to be the cause, Ill let engine cool and try induce the same with headlights.

Never the less I still need to clean the MAF.

Ill keep you all posted.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 12:59
by JoshJ
I wonder if this could not be earth related. A body earth that is not making good contact.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 15:46
by Louis Nel
I just spoke to a friend and he said it "Might"also be your Coolant Temp sensor. That sensor must tell the ECU how cold/hot the engine is at the given time, then the ECU will know exactly how much fuel and air to supply. He said maybe that sensor only reads 90 degrees which is operating temp, but anything before that it buggs out. Kinda makes sense cuz you said it runs fine once its at operating Temp.

Also got this from Aussie Forum on the same kind of topic.
Q.
I was wondering if anyone has had some experience with an erratic idle to the the point of stalling at times only on cold starts.After 20 secs or so it is back to normal and and no probs till next cold start.2002 gu3 4.8 ti 150k on clock petrol only.cheers..

A.
Usually its related to a coolant temp censor but they can be a bit expensive but what you can do is clean your AFM but be carefull not to wreck the little filament in it and also clean the idle speed motor and lubricate it try not to break the gasket. You can use carby cleaner and crc / wd40 to lub. Cheers

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 18:23
by karldDanneberg
JoshJ wrote: 27 Dec 2017 12:59 I wonder if this could not be earth related. A body earth that is not making good contact.
Thanks Josh, Ill also disconnect my dual battery ctek system (in Troll fridge) and HBC solenoid (trailer) to rule out a bug in this system. As this may be the most logical earthing issue.
Beyond this...im stumped.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 18:26
by karldDanneberg
Louis Nel wrote: 27 Dec 2017 15:46 I just spoke to a friend and he said it "Might"also be your Coolant Temp sensor. That sensor must tell the ECU how cold/hot the engine is at the given time, then the ECU will know exactly how much fuel and air to supply. He said maybe that sensor only reads 90 degrees which is operating temp, but anything before that it buggs out. Kinda makes sense cuz you said it runs fine once its at operating Temp.

Also got this from Aussie Forum on the same kind of topic.
Q.
I was wondering if anyone has had some experience with an erratic idle to the the point of stalling at times only on cold starts.After 20 secs or so it is back to normal and and no probs till next cold start.2002 gu3 4.8 ti 150k on clock petrol only.cheers..

A.
Usually its related to a coolant temp censor but they can be a bit expensive but what you can do is clean your AFM but be carefull not to wreck the little filament in it and also clean the idle speed motor and lubricate it try not to break the gasket. You can use carby cleaner and crc / wd40 to lub. Cheers
Excellent thanks Louis, I never thought of this...then again my mechanical skills is rather lacking. :lol:

Ill investigate and revert. I appreciate the help.

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 27 Dec 2017 22:20
by hugejp
Yes, please let us know where the gremlin is...

:thumbup:

Re: 4.8 Engine Sputter Rev Bounce at 2000 rpm

Posted: 28 Dec 2017 12:33
by Louis Nel
Right this is what my friend texted me this morning on whatsapp.

Louis dit kan n klomp goed wees, dit kan die
Water Temp sensor
Barometric pressure sensor
air temp sensor
coil of disi
MAF
throttle position senor wees

Wat ek voorstel as die ou nie diagnostics op die kar kan doen nie,
Begin by n punt, start en sien of hy die limiter het, as hy dit het plug die maf seonsor uit en kyk of daar n verskil is.
Tot hy n sensor kry wat nie n verskil maak nie.
Se vir hom om iemand met n ordentlike diagnostic te kry om net n scan te doen en dalk die actual values te kyk as die kar lop en limiter maak.

That is all I have on this. Hope it helps :)
All the best!